Field of the Invention
The invention relates in general to a display apparatus, and more particularly to a technology for correcting a display apparatus.
Description of the Related Art
With the flourish of various electronic products, multimedia systems such as home theaters have become popular. One of the most critical hardware devices in most multimedia systems is a display apparatus. Manufacturers or brands of display apparatuses have individual preferences regarding color performances of these display apparatuses, with however a common goal of showcasing brand features or maintaining product consistency. As color performances of each batch of panels may slightly vary due to minute differences in manufacturing processes, manufacturers usually need to test and correct color display settings before shipping a new batch of products out of the factory.
In one conventional approach, a testing staff first selects a bench that satisfies the expected color performance, and measures respective color performances of the bench corresponding to various input signals to accordingly establish a database. Assuming that the grayscale range of the bench is 0 to 255, when 9 grayscale values (0, 31, 63, 95, 127, 159, 191, 223 and 255) of red, green and blue are respectively selected and arranged in different combinations, there are a total of 729 (=9*9*9) grayscale combinations. The testing staff may enter these 729 grayscale combinations into the bench, and respectively measure the CIE XYZ values of an output image of the bench to accordingly generate 729 sets of color performance reference data for the standard database of the bench. Next, the testing staff may sequentially enter multiple red/green/blue grayscale combinations to a display apparatus under test, and measure the CIE XYZ value of an output image of the display apparatus under test to establish a sample database including multiple sets of sample data. From the sample database, the testing staff may then select 729 sets of sample data of color performances respectively most approximate to the 729 sets of reference data to establish a three-dimensional mapping table. For example, assume the CIE XYZ value from the standard database corresponding to a red/green/blue grayscale value (0, 0, 0) is XRYRZR, and the sample data of the CIE XYZ value from the sample database most approximate to XRYRZR is a red/green/blue grayscale value (3, 7, 0). As such, the red/green/blue grayscale value (3, 7, 0) in the sample data is set to have a mapping relationship with the red/green/blue grayscale value (0, 0, 0) in the reference data. The mapping table is stored to an internal memory of the display apparatus. When the display apparatus under test later receives input data of the red/green/blue grayscale value (0, 0, 0), the display apparatus under test controls its driver circuit to send out the red/green/blue grayscale value (3, 7, 0) according to the above mapping relationship.
It is understandable that, as the number of sample data in the sample database gets larger, there is a greater possibility of finding a set of sample data with a color performance that is more similar to a predetermined set of reference data. For example, by testing all possible red/green/blue grayscale combinations of the display apparatus under test when establishing the sample database, there are a total of 16,777,216 (256*256*256) sets of sample data. However, the measuring task is extremely time consuming, making it almost infeasible to establish such sample database with a colossal data amount. Therefore, the number of sets of sample data available for comparison is usually limited, such that a corrected display apparatus may still fail to achieve the color performance of the bench and to even result in a pointless pre-color correction procedure.